The invention relates to a process for the production of one or more light hydrocarbon oil distillates from a hydrocarbon oil residue obtained by atmospheric distillation.
During the atmospheric distillation of crude oil, as employed on a large scale in the refineries for the production of light hydrocarbon oil distillates, a residual oil is obtained as a by-product. In some cases this residual oil is suitable to serve as base i.e. starting material for the production of lubricating oil, but often the residual oil, which as a rule contains considerable quantities of sulfur, metals and asphaltenes, only qualifies for use as fuel oil.
In view of the growing need for light hydrocarbon oil distillates various processes have been proposed over the years which aimed at the conversion of the residual oils into light distillates. Exemplary processes include catalytic cracking, thermal cracking, gasification in combination with hydrocarbon synthesis, coking and hydrocracking. The use of the residual oils as such as feed for each of these processes has considerable disadvantages, which seriously hamper their application on a commercial scale. For instance, the catalytic cracking of these residual oils has the serious drawbacks that catalyst consumption is very high and that owing to the high coke and gas production only a low yield of the desired light distillates is obtained. The thermal cracking of these residual oils for the production of light distillates is not attractive either, because the stability of the cracked product permits only a low conversion to desired light distillates. Coking of the residual oils yields a considerable quantity of coke as product and this coke production occurs at the expense of the yield of desired light distillates. Gasification of the residual oils in combination with hydrocarbon synthesis is rather expensive and moreover not very attractive because in this way first the too heavy molecules are cracked to form too light molecules, the latter subsequently being recombined to form heavier ones. The hydrocracking of the residual oils is accompanied by a rapid catalyst deactivation and/or a high production and/or a high consumption of hydrogen.
In view of the above and taking into account the fact that in the atmospheric distillation of crude oil about half of the crude oil is left behind as distillation residue, it will be clear that there is a pressing need for a process which offers the possibility of converting in an economically justifiable way hydrocarbon oil residues obtained by atmospheric distillation into light, i.e. low boiling hydrocarbon oil distillates such as gasolines.
As in practice catalytic cracking has proved to be an excellent process for the conversion of heavy hydrocarbon oil distillates such as gas oils into light hydrocarbon oil distillates such as gasolines, the applicants have carried out an investigation in order to find out what use could be made of catalytic cracking for the conversion of hydrocarbon oil residues obtained by atmospheric distillation. It has been found that in a certain combination of catalytic cracking with catalytic high-pressure hydrotreatment, catalytic low-pressure hydrotreatment, deasphalting, gasification and thermal cracking or coking, a process can be realized which is highly suitable for this purpose. The present patent application relates to such a process.